相对封闭 Li-O2 电池阴极 Li2O-Li2O2-LiO2 电化学可逆转变过渡金属氧化物催化剂的制备和研究

Lithium-O2 battery is attracting much more attention due to its advantage in weight and its theoretical energy density of about 11,680 Wh/Kg, almost equivalent to petro engine. However, since Li2O2 is the main discharge product at cathode, the specific energy density and cycle life of Li-O2 batteries are significantly lowered due to many factors, such as big over potential gap between charging and discharging (1.2 V), low electronic and ionic conductivity of Li2O2 and the long - term stability of the electrolyte. We propose a study to prepare transition metal oxides with similar structure to absorbed O2- species or LiO2 (condensed) as catalysts, with special nano-structures to ensure tight contact with Li species and nucleation site to stabilize crystalline LiO2 the discharging product, which is good both in ionic and electronic conductivity. Then to build, characterize and evaluate the relatively closed Li-O2 battery system. The consistent intake of extra O2 at discharging or evolution of O2 at charging is no longer indispensible formation for some time to the system, therefore, the big over potential gap and a series of problems related to the gap are out of the question. At last, by optimizing catalysts, electrode structures and electrolytes, the cathodes polarization will be further researched and reduced. Hopefully, the specific energy density, cycle life and safety of the relatively closed Li-O2 batteries will be greatly promoted.

Li-O2电池因其重量轻以及几乎与燃油内燃机相当的理论能量密度（11,680 Wh/Kg），其研究备受关注。但由于Li2O2 通常是该体系主要的阴极放电产物，电池的比能量密度和循环使用寿命由于大的充放电过电势差（>1.2 V），Li2O2的低导电能力以及电解质的稳定性差而大大降低。本项目首先制备与O−2（凝聚态）吸附物种或LiO2晶种结构类似的过渡金属氧化物催化剂，使其与锂物种和氧物种在界面处紧密接触，实现阴极的放电产物为稳定的导电能力好的LiO2；搭建、表征和评价相对封闭的Li-O2电池体系。该电池经化成后，阴极完全没有气态氧的参与和生成，从而原则上解决了过大超电势差所带来的一系列问题。最后通过调变催化剂、电极设计以及电解液的组成，进一步降低阴极充放电反应的极化，提高该电池体系的能量密度、安全性和使用寿命。

Li-O2电池因其重量轻以及几乎与燃油内燃机相当的理论能量密度11,680KWh/Kg），其研究备受关注。但由于Li2O2;通常是该体系主要的阴极放电产物，电池的比能量密度和循环使用寿命由于大的充放电过电势差（>1.2 V），Li2O2的低导电能力以及电解质的稳定性差而大大降低。.本项目提出搭建相对封闭Li-O2电池(RCLO)，只在化成阶段氧气参与反应生成必要的氧物种，然后通过O 2-、O2 2-和O2 -之间的可逆转换，完成电池过程。本项目制备了由多壁碳纳米管(MWCNTs)为主体结构框架，担载αMnO2纳米线的正极催化剂。表面增强拉曼表征结果可见该催化剂能够捕捉相对封闭体系锂氧池电解液在正极处的锂离子，而且其多个共存的氧物种使化成阶段生成的氧化锂O2- 得到相对稳定，锂离子与超氧离子结合形成超氧化锂反应的活化能被降低，最终实现电池中导电性能较好的超氧化锂和其它锂的氧化物的可逆转化。使用该催化剂的相对封闭体系锂-氧电池，可以稳定循环133个周期，且在100 mA/g（催化剂质量）的电流密度下恒流放电，放电比容量为325mAh/g（催化剂质量）。以此为基础，搭建相对封闭锂-氧电池，并点亮46个额定电压为1.8V的发光二级管，工作 100分钟，循环工作4次。.本研究完成了预期研究内容，实现了预期研究目的，为推进金属空气电池、特别是锂空电池的市场化进程开辟了一条新的思路。